Wireless Thermostat Send-on-Delta Control for Battery Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless thermostats experience rapid battery depletion due to high power draw from wireless radio transmissions, leading to frequent battery replacements and reduced wireless range, which affects building temperature control.
Innovation Solution
Implementing a send-on-delta (SOD) method and deadband filtering in the thermostat's processing circuit to minimize data transmission frequency, using the SOD method to transmit temperature data only when the temperature error exceeds a threshold and the minimum time has passed since the last transmission, and employing deadband filtering to stabilize control signals and reduce unnecessary transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless radio transmissions are used for data communication, then wired communication is eliminated and installation flexibility is improved, but power consumption increases and battery life decreases
Solution Approach 1:
The thermostat uses periodic transmission intervals where the wireless radio transmits data at predetermined time intervals rather than continuously. The processing circuit determines when to transmit based on elapsed time since the last transmission, allowing the radio to remain in low-power mode between transmissions while still providing timely temperature data updates to the controller.
Solution Approach 2:
The system dynamically adjusts transmission timing based on temperature error conditions. When the temperature error exceeds a threshold, the thermostat triggers an immediate transmission regardless of the periodic interval, optimizing power consumption while ensuring critical temperature data is communicated promptly for HVAC control decisions.
2Ease of operation
If wireless radio transmissions are used for data communication, then wired communication is eliminated, but battery replacement frequency increases
Solution Approach 1:
The processing circuit implements periodic transmission scheduling where the wireless radio transmits temperature data at predetermined time intervals. This reduces the overall transmission frequency compared to continuous transmission, directly lowering the cumulative power draw from the battery and extending battery operational life while maintaining adequate temperature monitoring for HVAC control.
Solution Approach 2:
The thermostat autonomously manages its own power consumption by having the processing circuit determine transmission timing based on temperature error thresholds and time elapsed since last transmission. This self-regulating mechanism ensures transmissions occur only when necessary for effective HVAC control, minimizing unnecessary power consumption and battery replacement needs.
3Speed
If temperature data is transmitted frequently to the controller, then temperature control responsiveness is improved, but power consumption increases
Solution Approach 1:
The system uses periodic transmission intervals as the baseline strategy, where the wireless radio transmits data at predetermined time intervals rather than continuously. This reduces power consumption while maintaining adequate responsiveness for HVAC control, as the periodic updates provide the controller with sufficient temperature information to make effective control decisions without requiring constant data streams.
Solution Approach 2:
The processing circuit uses feedback from temperature error calculations to trigger transmissions. When the temperature error exceeds a predetermined threshold, the system immediately transmits data regardless of the periodic interval, ensuring responsive HVAC control when temperature deviations occur while maintaining energy efficiency during stable temperature conditions.
Data Source
AI summary
A thermostat for transmitting data wirelessly to a controller in a building includes a temperature sensor, a processing circuit, and a wireless radio. The processing circuit is configured to receive a measured temperature value from the temperature sensor, determine a current temperature error based on the current measured temperature value and a setpoint temperature, and determine whether a difference between the current temperature error and a previous temperature error is greater than an error threshold. The processing circuit is configured to determine whether a minimum amount of time has passed since transmitting a previous measured temperature value and transmit the current measured temperature value to the controller via the wireless transmitter in response to determining that both the difference between the current temperature error and the previous temperature error is greater than the error threshold and the minimum amount of time has passed since transmitting a temperature value.